Pump Assembly Having an Axial-Flux Electric Drive

ABSTRACT

The invention relates to a pump assembly, at least comprising a first housing, in which at least one first drive means for conveying a fluid is rotatably mounted, wherein a first drive shaft of the first drive means extends at least through a first side wall of the first housing in an axial direction; wherein, outside of the first housing, at least one first rotor of a first axial-flux electric drive is arranged on the first drive shaft, wherein the first axial-flux electric drive has only one stator.

The present invention relates to a pump arrangement at least comprising a first housing in which there is arranged in a rotatably mounted manner at least one first drive means for delivering a fluid, wherein a first drive shaft of the first drive means extends at least through a first side wall of the first housing along an axial direction. The pump arrangement is in particular a delivery device for a water-urea solution (for example Adblue), which is preferably used in a motor vehicle for treating an exhaust gas of an internal combustion engine.

Such pump arrangements for water-urea solutions have long been known. Here, it is normally the case that an electric drive unit is connected to the drive shaft of the drive means. The drive means for delivering a fluid is driven via the drive shaft of such rotation pumps. Gearwheel rotors (in the case of gearwheel pumps) are known for example as drive means. A pump arrangement which is as compact as possible is to be provided particularly for the use in motor vehicles, wherein noises of the pump arrangement, in particular, are to be avoided as much as possible. Furthermore, in the case of the delivery of water-urea solutions, care should be taken that freezing of the solution in the lines is avoided as much as possible. Therefore, the water-urea solution is normally delivered back into a storage tank from the line. For this purpose, however, the drive means is also to be driven in the opposite direction of rotation.

Taking this as a starting point, it is an object of the present invention at least to lessen or even to solve the problems highlighted with regard to the prior art. In particular, it is sought to propose a compact pump arrangement which is characterized by low noise development.

In order to achieve said objects, a pump arrangement as per the features of claim 1 is proposed. Advantageous embodiments are the subject of the dependent claims. The features set out individually in the claims are able to be combined with one another in a technologically meaningful way and can be supplemented by explanatory substantive matter from the description and details from the figures, wherein further embodiment variants of the invention are demonstrated. The invention relates to a pump arrangement at least comprising a first housing in which there is arranged in a rotatably mounted manner at least one first drive means for delivering a fluid, wherein a first drive shaft of the first drive means extends at least through a first side wall of the first housing along an axial direction, wherein, outside the first housing, at least one first rotor of a first axial flux electric drive is arranged on the first drive shaft, wherein the first axial flux electric drive has only one stator, this being a first stator associated with the first axial flux electric drive and the first rotor, and thus in particular no further (second) stator.

In particular, the first housing encloses at least the first drive means in a liquid-tight manner, wherein connections for feeding and discharging the fluid to be delivered are provided. The first drive shaft extends through a first side wall of the first housing, wherein also here, liquid-tight sealing between the first side wall and the first drive shaft is provided. Outside the first housing, a first rotor of a first axial flux electric drive (AFM: axial flux motor) is provided, which rotor is arranged on the first drive shaft for the purpose of transmitting a torque to the first drive means. As a result of the separate arrangement of drive means and electric drive, it is possible to avoid the electric drive being damaged by the delivered fluid.

In particular, the first housing encloses at least the first drive means, wherein connections for feeding and discharging the fluid to be delivered are provided. The first drive shaft extends through a first side wall of the first housing. Outside the first housing, a first rotor of a first axial flux electric drive (AFM: axial flux motor) is provided, which rotor is arranged on the first drive shaft for the purpose of transmitting a torque to the first drive means. Preferably, the first housing is not of liquid-tight form, so that the fluid to be delivered can, as a leakage flow, exit the first housing for example along the first drive shaft. However, the first housing is preferably formed such that said leakage flow from the first housing (that is to say a fluid outflow and/or fluid inflow not exclusively via the connections for feeding and discharging the fluid) does not result in any significant impairment of the delivery capacity of the pump arrangement. In particular, the leakage flow amounts to at most 5% of the delivery capacity (of the delivery volume flow) of the pump arrangement.

The first axial flux electric drive comprises a (single) stator and a first rotor, which are arranged coaxially with respect to one another. The stator may comprise a soft magnetic material, for example a so-called “soft magnetic composite” (SMC), or a combination of electric sheet steels and SMC. The coils of the stator comprise cores which are preferably produced by being compacted and baked from a soft magnetic material. In this case, the SMC material is not sintered. Rather, temperature control to below a melting temperature is realized, which, however, is sufficient for the cores to permanently retain their geometry.

The rotor of the axial flux electric drive may have permanent magnets or else soft magnetic elements, for example in recesses. It is thus possible, by way of permanent magnets, to form a permanently excited synchronous or brushless DC motor, abbreviated as BLDC, as an axial flux electric motor, while, for example, by way of soft magnetic elements, a reluctance motor can be created as an electric motor with an axial design.

The construction of a stator, in particular through the use of SMC, and further details also concerning a rotor are described for example in PCT/EP2015/075036, which is a later publication of the applicant and to which reference is made within the context of the disclosure of the present invention.

The first axial flux electric drive has in particular an electrical power consumption of less than 100 watts, preferably of less than 50 watts. In particular, the fluid is delivered at a delivery pressure of at most 10 bar.

According to a preferred embodiment, outside the first housing, the first drive shaft is not mounted or is mounted by way of at least one bearing, which exclusively accommodates forces acting in the axial direction. It is thus in particular the case here that no radial bearing, that is to say a bearing which serves for providing support with respect to forces acting in the radial direction, is required outside the first housing. Thus, the first drive shaft is in particular exclusively mounted in the first housing, with the result that there is no requirement for the structural space for bearings, which are otherwise needed, outside the first housing. In this way, a particularly compact design of the pump arrangement is possible.

As bearings, use may be made in this case of so-called friction bearings or slide bearings. Preferably, at least the first drive shaft is mounted exclusively via the first housing, for example via the first side wall and/or a second side wall, wherein in particular the material of the side walls forms the bearing surface.

It is in particular the case here that a leakage flow of the fluid along the first drive shaft, which fluid is to be delivered, can bring about lubrication of the bearings. Preferably, a pressure chamber of the pump arrangement is fluidically connected to a region outside the first housing via an opening at least in the first side wall. In this way, it is possible for a volume flow of the fluid to be delivered, which volume flow is controlled (with regard to quantity), to exit the first housing and to flow back into the first housing via the bearings.

According to a further advantageous embodiment, the first axial flux electric drive is arranged in a second housing which is able to be connected in a repeatably detachable manner to the first housing. In this way, the first axial flux electric drive is arranged so as to be protected with respect to the fluid to be delivered, wherein the individual components of the pump arrangement are replaceable, and/or to be maintained, independently of one another.

In particular, the first rotor is arranged directly adjacent to the first side wall and between the first side wall and a stator of the first axial flux electric drive. With this arrangement, the first drive shaft can be of very short form since the first rotor, which is connected to the first drive shaft, is arranged directly adjacent to the first face wall, through which the first drive shaft extends into the second housing from the first housing.

According to another embodiment, a stator of the first axial flux electric drive is arranged directly adjacent to the first side wall and between the first side wall and the first rotor. Here, the first drive shaft is to be of longer form since it extends to the first rotor also through the stator.

Preferably, the stator (that is to say its components, in particular coils, cores and return ring) is arranged outside the at least one first drive means in a radial direction.

Preferably, the stator (that is to say at least one of the components of coil, core and return ring) is arranged so as to overlap the first housing, preferably so as to overlap at least one bearing of the first drive shaft, particularly preferably so as to overlap the at least one first drive means, along the axial direction.

This preferred embodiment allows a particularly compact construction of the pump arrangement, wherein (exclusively) the at least one first drive means, the first side wall and the first rotor are arranged next to one another along the axial direction and thus determine the structural size of the pump arrangement along the axial direction.

In particular, the stator is inseparably connected to the first side wall. In particular, the stator forms at least a part of the first face wall.

Preferably, the first drive means is a first gearwheel rotor. This may be formed for example as a constituent part of a gearwheel pump, wherein the gearwheel pump may be constructed as an external-gearwheel pump with preferably an involute toothing, as an internal-gearwheel pump or else as a gear ring pump, for example as a gerotor pump or as a sickle-type pump. Furthermore, the gearwheel pump may be a screw-spindle pump.

In particular, at least the first gearwheel rotor is produced from a plastic.

It is in particular proposed to produce at least the first gearwheel rotor from a sintered material having a porosity, wherein the gearwheel rotor has, in addition to the porosity, a further sound-reducing means. Here, reference is made in particular to the content of DE 10 2015 201 873. It has been found that, by varying the density in the wheel body of the gearwheel rotor, the transmission path of the structure-borne sound waves from the generation at the gear ring to the hub can be interrupted or the sound waves can be broken or reflected such that the structure-borne sound signal at the output, namely the shaft/bore of the gearwheel rotor, is significantly reduced. The density variations may in this case be realized in a rotationally symmetric or local manner. A gearwheel rotor in disk arrangement with differently realized densities is equally possible. The angle of the plane of the individual layers may in this case deviate from the reference plane, the horizontal plane of the component. Since the structure-borne sound propagates better in materials with a relatively high density than in materials with a relatively low density, it is also possible to introduce into the gearwheel rotor, or only into the toothing, sound-guiding channels which deflect or attenuate the structure-borne sound waves in a targeted manner. Here, the channels and/or local density variations may be filled both with pure material of different density and also with combinations of different materials, such as iron powder or even oil.

These sound-reducing geometries may be realized with different production methods. These include, for example, an intelligent filling shoe, in particular a rotating filling shoe for filling with at least two different materials, in the manner described for example in DE 10 2014 006 374. In this way, it is possible for example for density variations to be produced already during the pressing process. Furthermore, it is also possible for use to be made of a production method referred to as a “green-to-green” production method, as is described in DE 10 2009 042 598, in order, for example, to generate density variations. Production methods such as conventional pressing of metallic powder, as is described, also in modified form, in WO 2013/067995 A1, and additive production of metallic material and/or plastic, for example by way of a device which is described for example in DE 10 2013 103006 A1, may likewise be used, in particular to produce low-noise gearwheel rotors. It is, however, also possible for use to be made of production methods which are basically described in EP 2 221 131 A1, EP 1 407 877 A1, EP 1 34527 A2 or else JP S60-162 702 A.

One embodiment provides that the stator is formed by the first housing. For example, the stator may be embedded into the first housing for this purpose. This is possible for example by means of a green-to-green method, which has already been described above and to which reference is made in this respect. It is also possible for the stator to be inserted into the first housing. It is thus possible, for example, for an outer side of the first housing to have a cutout into which the stator can be pressed. For example, the first housing may be composed of plastic in this region, while the stator is produced from metallic material. For example, a return ring on which the stator poles are arranged may be pressed in.

In this embodiment, it is advantageous in particular if the stator (that is to say at least one of the components of coil, core and return ring) is arranged so as to overlap at least one bearing of the first drive shaft, particularly preferably so as to overlap the at least one first drive means.

It is preferable for the first housing to have a non-magnetic material at least in a region adjacent to the stator, preferably to the electromagnetic return (ring) and in particular to the cores of the stator. In this way, the required formation of the electromagnetic field for generating a torque at the rotor of the axial flux motor is undisturbed or is disturbed only to a small extent.

According to a further advantageous embodiment, a second axial flux electric drive is arranged outside the first housing and on a second side wall, opposite the first side wall, of the first housing, wherein the second axial flux electric drive is connected in a torque-transmitting manner either to the first drive shaft or to a second drive shaft of a second drive means which is arranged in the first housing.

In particular, the second axial flux electric drive is connected in a torque-transmitting manner to the second drive shaft, wherein the second drive means is a second gearwheel rotor which is arranged so as to mesh with the first gearwheel rotor for delivering the fluid, wherein the two gearwheel rotors are arranged so as to be braced with respect to one another via the two axial flux electric drives.

The bracing of the two gearwheel rotors brings about a constantly play-free meshing of the gearwheel rotors, with the result that noises are able to be minimized. It is in particular possible for said bracing to also be set when reversing the direction of rotation of the drive means (for example when delivering a water-urea solution back into a tank for the purpose of avoiding ice formation in the lines).

According to a further embodiment, although the two axial flux electric drives are of the same construction, they are arranged offset from another, with regard to the arrangement of the stator poles, at opposite ends of the gearwheel rotor. By way of an offset, it is possible for example to realize a balance between generated electromagnetic waves of the axial flux electric drive. For example, depending on the construction of the axial flux electric drives, the offset may be configured such that the wave trough caused by the first axial flux electric drive and the wave peak caused by the second axial flux electric drive more or less overlap in their torque effect. A more balanced, in particular more even, drive of the gearwheel rotor is thereby achieved. This in turn leads to a reduction in noise emissions at the intermeshing gearwheels. The evening out of the torque at the driven shaft in particular leads to quieter contacting of the individual teeth of the intermeshing gearwheels. Impacting of the intermeshing teeth can be at least minimized.

In particular, at least the first axial flux electric drive forms at least one heating element which is connected in a heat-conducting manner to the first side wall via at least one heat-conducting structure. As a heating element of the first housing, use may in particular be made of the one stator with its coils. The heat generation arising there may, for example, be introduced in a conductive manner into the first housing via the first side wall. For this purpose, the power electronics allow for example a corresponding current to be provided, which flows through the coils of the stator poles. In order to provide good heat transfer, it is particularly advantageous if the stator is, with its rear surface, fully connected to the first housing, and thus forms for example the first side wall itself. Therefore, the stator is placed as first side wall preferably directly onto the first housing or is inserted for example into a first side wall which is formed as a lid of the first housing.

In order to produce the stator or the first side wall or heat-conducting structures, it is possible for example for a metallic, electrically conductive powder to be co-utilized, for example in the case of a rotating filling shoe for filling with at least two different materials, in the manner described for example in DE 10 2014 006 374. This, for example, allows not only density variations but also conductive heat paths (heat-conducting structure) and electrically heatable paths (heat-conducting structure) to be produced already during the pressing process (of the stator, of the first side wall).

The first side wall forms in particular at least a part of a fluid-conducting channel. Preferably, at least a part of the side wall makes contact with the delivered fluid in the region of the channel (for example in the region of the drive means). In particular, only this part-region is formed with a heat-conducting structure, with the result that the heat generated in the region of the stator can be released to the fluid in a targeted manner via the heat-conducting structure.

For the heat generation, it is possible for example to resort to a temperature sensor. Such a temperature sensor may be attached to the pump arrangement itself. A further embodiment provides that use is made of a provided temperature sensor at power electronics of the pump arrangement in order to decide whether and how intensely a current is passed through the stator. Such information can be stored for example in a control unit which is associated with the urea injection. Thus, for example, when detecting temperatures which are too low, the heating can be realized already before the actual start of the internal combustion engine. If keyless systems of today for opening and starting are considered, it would therefore be possible for the precautionary heating to already be activated by the opening. In this way, heating of the pump itself would be possible, which for example is supplemented with heat which originates for example from a tank heater or as waste heat from an internal combustion engine which is still warm. It would thus be possible for the system to be immediately operational, or to remain operational, even at low temperatures.

Furthermore, according to an embodiment, it is provided that compensation for a different heat expansion of the different materials in the pump arrangement is provided. The fluid or the urea solution can be exposed to temperatures which, due to the surroundings and also operational circumstances, can vary intensely, for example in the case of deep frost of for example −35° C. and owing to the conditions during injection of the urea solution of, at least for a brief period, +100° C. This likewise has an effect on the individual components which already expand and contract in a different manner owing to the temperature of the surroundings. Therefore, the pump arrangement may for example have a spring-loaded readjusting means in its interior, which for example permits a minimization of gap dimensions which otherwise arise.

The use of the pump arrangement according to the invention for delivering a water-urea solution in a motor vehicle is proposed.

In addition to a first gearwheel, the motor vehicle urea pump may also have a second gearwheel on a second shaft, wherein the two gearwheels mesh with one another and, in the process, build up a pressure. Both gearwheels may be constructed from the same material. However, it is also possible for the two gearwheels to be constructed from mutually different materials. For example, the one gearwheel may be composed of a plastic, and the other gearwheel may be composed of a metal. Also, use may be made of composite gearwheels, that is to say the gearwheel has different materials, for example a core composed of metal and a surface composed of plastic, or vice versa. In the case of intermeshing gearwheels, use is preferably made of bevel-toothed gearwheels. However, for the pressure elevation, it may likewise be advantageous to use straight-toothed gearwheels. Preferably, the gearwheel(s) is/are produced as spur-gear gearwheels with a production quality in which the gearwheel has, with regard to at least one parameter, preferably a total profile error F_(α), a profile angle error f_(Hα) and a profile form error f_(α), a quality of the designed gearwheel according to DIN 3961 and DIN 3962 of at least 6, preferably of at least 5 or better, for at least one of these values, in particular at least these three values. For example, the first housing may also have additional damping, by means of which a pump noise is reduced. Such density variations as described above may, for example, be used here. Other possibilities described here for minimizing a structure-borne sound in or on the housing may also be used to realize the additional damping.

Furthermore, damping of a noise or a noise spectrum may be realized not only by different sintered materials and/or densities in the case of sintered materials. It is also possible for damping to be set in a targeted manner by targeted open porosity of the sintered material or closure of pores, for example through the addition of copper, for example in connection with different densities, if appropriate by using green-to-green production methods with inner and outer material, and also by one or more coatings of components, for example with a plastic.

The invention and the technical field will be explained in more detail below on the basis of the figures. It is to be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the explanatory substantive matter in the figures and to combine these with other parts and findings from the present description including figures. The same reference signs are used to denote identical objects, and so, if appropriate, explanations from other figures may be used in a supplementary manner. In the drawings:

FIG. 1 schematically shows an exploded illustration of a first pump arrangement in a perspective view;

FIG. 2 schematically shows the exploded illustration of the first pump arrangement as per FIG. 1 in a side view in section;

FIG. 3 schematically shows the first pump arrangement as per FIGS. 1 and 2 in a side view in section;

FIG. 4 schematically shows the first pump arrangement as per FIG. 3 in a plan view;

FIG. 5 schematically shows an exploded illustration of a second pump arrangement in a perspective view;

FIG. 6 schematically shows the exploded illustration of the second pump arrangement as per FIG. 5 in a side view in section;

FIG. 7 schematically shows the second pump arrangement as per FIGS. 5 and 6 in a side view in section;

FIG. 8 schematically shows a third pump arrangement in a side view;

FIG. 9 schematically shows a fourth pump arrangement in a side view;

FIG. 10 schematically shows a fifth pump arrangement in a side view; and

FIG. 11 schematically shows a sixth pump arrangement in a side view.

FIG. 1 shows an exploded illustration of a first pump arrangement 1 in a perspective view. FIG. 2 shows the exploded illustration of the first pump arrangement 1 as per FIG. 1 in a side view in section. FIG. 3 shows the first pump arrangement 1 as per FIGS. 1 and 2 in a side view in section, and FIG. 4 shows the first pump arrangement 1 as per FIG. 3 in a plan view. FIGS. 1 to 4 will be described jointly below. Feed and discharge lines for the fluid 4 and electrical components (control unit, electrical connections, etc.) are not shown here since the arrangement thereof is normally known to a person skilled in the art.

The pump arrangement 1 comprises a first housing 2, which has a first side wall 6 and a receptacle 10 for the drive means 3, 21 (two intermeshing gearwheel rotors in this case). The drive means 3, 21 are arranged in a rotatably mounted manner in the first housing 2 for delivering a fluid 4, wherein a first drive shaft 5 of the first drive means 3 extends through the first side wall 6 of the first housing 2 along an axial direction 7. Outside the first housing 2, a first rotor 8 of a first axial flux electric drive 9 is arranged on the first drive shaft 5.

The first housing 2 encloses the drive means 3, 21 in particular in a vapor-tight and liquid-tight manner, wherein connections for feeding and discharging the fluid 4 to be delivered are provided. The first drive shaft 5 extends through a first side wall 6 of the first housing 2, wherein also here, liquid-tight sealing between the first side wall 6 and the first drive shaft 5 is provided. The first axial flux electric drive 9 comprises a (first) stator 13 and a first rotor 8, which are arranged coaxially with respect to one another. The coils 15 of the stator 13 interact with magnets 22 of the first rotor 8 to generate a torque for driving the first rotor 8, and thus the first drive shaft 5, in the circumferential direction 16. The stator 13 has a plurality of coils 15 which are arranged uniformly spaced apart from one another in a circumferential direction 16 on a return plate of the stator 13.

The first drive shaft 5 is mounted via radial bearings (which accommodate forces in the radial direction 24) and, if appropriate, axial bearings (which accommodate forces in the axial direction 7) only within the first housing 2. Outside the first housing 2, the first drive shaft 5 is arranged in a non-mounted manner.

The first axial flux electric drive 9 is arranged in a second housing 12 which is able to be connected in a repeatably detachable manner to the first housing 2. In this way, the first axial flux electric drive 9 is arranged so as to be protected with respect to the fluid 4 to be delivered, wherein the individual components of the pump arrangement 1 are replaceable, and/or to be maintained, independently of one another.

Here, the first rotor 8 is arranged directly adjacent to the first side wall 6 and between the first side wall 6 and the stator 13 of the first axial flux electric drive 9. With this arrangement, the first drive shaft 5 can be of very short form since the first rotor 8, which is connected to the first drive shaft 5, is arranged directly adjacent to the first face wall 6, through which the first drive shaft 5 extends into the second housing 12 from the first housing 2.

The stator 13 comprises a soft magnetic material 17, for example a so-called “soft magnetic composite” (SMC), or a combination of electric sheet steels and SMC.

FIGS. 5 to 7 show a second pump arrangement 1. FIG. 5 shows an exploded illustration of a second pump arrangement 1 in a perspective view. FIG. 6 shows the exploded illustration of the second pump arrangement 1 as per FIG. 5 in a side view in section. FIG. 7 shows the second pump arrangement 1 as per FIGS. 5 and 6 in a side view in section.

Reference is made to the embodiments relating to FIGS. 1 to 4. Here, by contrast to the first pump arrangement 1, the first rotor 8 and the stator 13 are arranged the other way round. Here, the stator 13 of the first axial flux electric drive 9 is arranged directly adjacent to the first side wall 6 and between the first side wall 6 and the first rotor 8. Here, the first drive shaft 5 is to be of longer form since it extends to the first rotor 8 also through the stator 13.

Here, as a heating element 25 of the first housing 2, use may be made of the stator 13 with its coils 15. The heat generation arising there may, for example, be introduced in a conductive manner into the first housing 2 via the first side wall 6. For this purpose, the power electronics allow for example a corresponding current to be provided, which flows through the coils 15 of the stator poles of the stator 13. In order to provide good heat transfer, the stator 13 is, with its rear surface, fully connected to the first housing 2, and thus to the first side wall 6 here.

The first side wall 6 forms at least a part of a fluid 4-conducting channel (in the region of the first drive means 3 and of the second drive means 21). In this case, at least a part of the first side wall 6 makes contact with the delivered fluid 4 in the region of the channel (for example in the region of the drive means 3, 21). Here, a heat-conducting structure 26 is formed only in this part-region, with the result that the heat generated in the region of the stator 15 can be released in a targeted manner to the fluid 4 via the heat-conducting structure 26.

FIG. 8 shows a third pump arrangement 1 in a side view. Reference is made to the embodiments relating to FIGS. 1 to 7. Here, by contrast to the first and second pump arrangement 1, a second axial flux electric drive 18 is arranged outside the first housing 2 in a third housing 23 and on a second side wall 19, opposite the first side wall 6, of the first housing 2. The second axial flux electric drive 18 is connected in a torque-transmitting manner to a second drive shaft 20 of the second drive means 21, which means is arranged in the first housing 2, wherein the second drive means 21 is a second gearwheel rotor which is arranged so as to mesh with the first gearwheel rotor for delivering the fluid 4.

FIG. 9 shows a fourth pump arrangement 1 in a side view. Reference is made to the embodiments relating to FIG. 8. By contrast to the third pump arrangement 1, the second axial flux electric drive 18 is connected in a torque-transmitting manner to the first drive shaft 5.

FIG. 10 shows a fifth pump arrangement 1 in a side view. Reference is made to the embodiments relating to FIGS. 5 to 7. By contrast to FIGS. 5 to 7, the stator 13 (that is to say its components coils 15, cores and return ring 14) is arranged outside the at least one first drive means 3 in a radial direction 24. In this case, the stator 13 (that is to say at least one of the components of coils 15, cores and return ring 14) is arranged so as to overlap the first housing 2, in this case so as to overlap at least one bearing 11 (radial bearing, axial bearing, slide bearing, friction bearing) of the first drive shaft 5 and so as to overlap the at least one first drive means 3, along the axial direction 7. This preferred embodiment allows a particularly compact construction of the pump arrangement 1, wherein (exclusively) the at least one first drive means 3, the first side wall 6 (with the bearing 11 for example as a constituent part of the first side wall 6) and the first rotor 8 are arranged next to one another along the axial direction 7 and thus determine the structural size of the pump arrangement 1 along the axial direction 7.

FIG. 11 shows a sixth pump arrangement 1 in a side view. Reference is made to the embodiments relating to FIGS. 1 to 4. Here, by contrast to the first pump arrangement 1, the first drive shaft 5 is arranged so as to be mounted by way of a bearing 11 outside the first housing 2, wherein the bearing 11 exclusively accommodates forces acting in the axial direction 7. It is thus the case here that no radial bearing, that is to say a bearing 11 which serves for providing support with respect to forces acting in the radial direction 24, is arranged outside the first housing 2. Also here, the first drive shaft 5 is exclusively mounted in the first housing 2, with the result that there is no requirement for the structural space for bearings 11, which are otherwise needed, outside the first housing 2. In this way, a particularly compact design of the pump arrangement 1 is possible.

LIST OF REFERENCE SIGNS

-   1 Pump arrangement -   2 First housing -   3 First drive means -   4 Fluid -   5 First drive shaft -   6 First side wall -   7 Axial direction -   8 First rotor -   9 First axial flux electric drive -   10 Receptacle -   11 Bearing -   12 Second housing -   13 Stator -   14 Return ring -   15 Coil -   16 Circumferential direction -   17 Material -   18 Second axial flux electric drive -   19 Second side wall -   20 Second drive shaft -   21 Second drive means -   22 Magnet -   23 Third housing -   24 Radial direction -   25 Heating element -   26 Heat-conducting structure 

1. A pump arrangement comprising a first housing in which there is arranged in a rotatably mounted manner a first drive for delivering a fluid, wherein a first drive shaft of the first drive extends through a first side wall of the first housing along an axial direction, wherein, outside the first housing, a first rotor of a first axial flux electric drive is arranged on the first drive shaft, wherein the first axial flux electric drive has only one stator.
 2. The pump arrangement as claimed in claim 1, wherein, outside the first housing, the first drive shaft is not mounted or is mounted by way of a bearing, which exclusively accommodates forces acting in the axial direction.
 3. The pump arrangement as claimed in claim 1, wherein the first axial flux electric drive is arranged in a second housing which connectable in a repeatably detachable manner to the first housing.
 4. The pump arrangement as claimed in claim 1, wherein the first rotor is arranged directly adjacent to the first side wall and between the first side wall and a stator of the first axial flux electric drive.
 5. The pump arrangement as claimed in claim 1, wherein the stator is arranged directly adjacent to the first side wall and between the first side wall and the first rotor.
 6. The pump arrangement as claimed in claim 5, wherein the stator is arranged outside the first drive in a radial direction.
 7. The pump arrangement as claimed in claim 6, wherein the stator is arranged so as to overlap the first housing along the axial direction.
 8. The pump arrangement as claimed in claim 7, wherein the stator is arranged so as to overlap the first drive along the axial direction.
 9. The pump arrangement as claimed in claim 5, wherein the stator is inseparably connected to the first side wall.
 10. The pump arrangement as claimed in claim 1, wherein the first drive is a first gearwheel rotor.
 11. The pump arrangement as claimed in claim 1, wherein the stator of the axial flux electric drive comprises materials which comprise soft magnetic composite.
 12. The pump arrangement as claimed in claim 1, wherein the first axial flux electric drive forms a heating element which is connected in a heat-conducting manner to the first side wall via a heat-conducting structure.
 13. The pump arrangement as claimed in claim 1, wherein a second axial flux electric drive is arranged outside the first housing and on a second side wall, opposite the first side wall, of the first housing, wherein the second axial flux electric drive is connected in a torque-transmitting manner either to the first drive shaft or to a second drive shaft of a second drive which is arranged in the first housing.
 14. The pump arrangement as claimed in claim 13, wherein the second axial flux electric drive is connected in a torque-transmitting manner to the second drive shaft, and wherein the second drive is a second gearwheel rotor which is arranged so as to mesh with the first gearwheel rotor for delivering the fluid, wherein the two gearwheel rotors are arranged so as to be braced with respect to one another via the two axial flux electric drives.
 15. The use of the pump arrangement as claimed in claim 1, for delivering a water-urea solution in a motor vehicle. 